Passive solar cooling is one of the two design approaches of passive solar design. It means the utilization of design choices and materials to decrease heat gain and increase heat loss.
The purpose of passive solar cooling is to dissipate heat inside a home if it becomes uncomfortably hot. So, it is specifically beneficial in hot and humid or hot and dry weather conditions.
A comfortable and cool temperature in a building can be maintained with less energy by using a combination of adequate insulation, daylighting, energy-efficient doors and windows, shading, and ventilation.
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Why is Passive Cooling Important?
- Passive cooling is the least expensive method for cooling a building.
- The adoption of a passive cooling design will reduce the utility bills and improve the indoor condition of the building.
How does Passive Cooling Work?
Movement of air is the key to almost all techniques of passive cooling. It needs well-designed openings and unobstructed breeze paths. The air carries heat out of the building and replaces it with cooler external air, resulting in reduction in the inside temperature of the building.
Some strategies of passive solar cooling include operable windows and doors, natural ventilation, wing walls, shades, insulations, thermal masses, and landscape and garden designs:
1. Ventilation and Operable Windows
The design and placement of windows in a building play a significant role in passive cooling.
Casement windows provide good airflow, but hopper windows offer the best rain protection. The hopper windows need to be opened completely; otherwise, the air will be directed toward the ceiling.
If a window needs to be placed at one side, provide two widely spaced windows rather than one.
2. Wing Wall
Wing wall is vertical solid panels installed alongside windows transverse to the wall on the windward side, see Figure-2. It increases the speed of the natural wind and subsequently improves the cooling effect inside the house.
3. Thermal Chimney
The provision of a thermal chimney is another way to improve the cooling effect in a building. It draws air out of the structure using convective currents.
Air can be drawn inside the building by generating a hot or warm zone with an exterior exhaust, hence ventilating the structure. Adequate detail of the thermal chimney is shown in Figure-3.
4. Internal Layout of the Building
The arrangements of walls, doors, and rooms influence the heat distribution within the building.
5. Thermal Mass
The function of thermal mass is absorbing heat during days to moderate internal temperature. During nights, thermal mass is cooled through the use of ventilation. This makes the thermal mass ready for the next hot days to absorb heat and avoid the rise of temperature in the living space.
6. Earth Coupling
Earth coupling is a technique that aids in achieving passive cooling in a building, see Figure-5. The earth coupling helps draw up the stable, deeper ground temperature to the floor's surface, providing the building a headstart to regulate temperature.
Earth coupling is particularly effective in a well-insulated and properly shaded house. It is beneficial in areas where deep earth temperatures are low at a depth of 3 m or more.
7. Insulation
Selecting suitable insulation products and paying attention to their placement will improve thermal comfort and avoid condensation.
Generally, applicable codes provide minimum insulation levels for floors, roofs, and walls based on the climate and other building features.
8. Shading Glazing
Shading windows is critical to prevent heat gain and improve the cooling effect. Based on the angle of the sunshine in winter or summer season, a designer can choose deep overhang shading or vertical shading to control heat gain.
If it is not possible to install proper shading, providing glass with a solar heat gain coefficient (SHGC) of not more than 0.20 is highly recommended. Double glazing is also helpful in achieving passive cooling as it has low conductivity, which reduces the effect of the hot air.
9. Landscape
Landscape helps cool homes and neighborhoods. For example, gardens and trees can reduce the heat of air flowing into the building.
FAQs
The passive solar cooling design is one of the two design approaches of passive solar design. It is the utilization design choices to decrease heat gain and increase heat loss.
The purpose of the passive solar cooling design is to dissipate heat inside a home.
1. Ventilation and Operable Windows
2. Wing Walls
3. Thermal Chimney
4. Internal Layout of the Building
5. Thermal Mass
6. Earth Coupling
7. Insulation
8. Shading Glazing
9. Landscape
1. Increases energy efficiency in a building,
2. Declines the environmental impacts of energy consumption,
3. Improves sound insulation,
4. Offers more appealing indoor spaces,
5. Enhances the quality of air inside the structure.
The passive cooling design strategies can be applied to both new and existing buildings. Nonetheless, it is much easier to use in new constructions.
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